Researchers from the California Institute of Technology and Washington University in St Louis have just published a paper in Nature Communications in which they described a hybrid imaging method to detect breast cancer. Lihong Wang and colleagues believe their technique, which they have called single-breath-hold photo-acoustic computed tomography (PACT), might some day offer a viable alternative to screening mammography which is based on ionizing X-rays. The authors acknowledge that their approach – which converts optical energy into acoustic energy – is not new, but what is new is their ability to generate high-resolution images with deep penetration.

The PACT system can penetrate 4 cm of breast tissue with high spatial resolution of 0.25 mm and good temporal resolution of 10 Hz for 2D acquisition. By scanning the ultrasound transducer vertically, from nipple to chest wall during a single breath hold of 15 seconds, a volumetric image can be acquired and reconstructed using 3D back-projection. Because PACT is able to measure the density of blood vessels – a harbinger of cancer cell proliferation – the system is able to reveal the presence of tumours.

PACT has been licensed by a company that plans to commercialise it. “Our goal is to build a dream machine for breast screening, diagnosis, monitoring and prognosis without any harm to the patient,” enthused Wang. “We want it to be fast, painless, safe and inexpensive. Now that’s something worth striving for!